Different types of analgesics and narcotic antagonists were examined by a variety of in vivo and in vitro techniques to discern their effect on the narcotic receptor. Brominated narcotic antagonists were prepared, as were agonist-antagonists with unusual substituents. A theoretical study was completed to relate antinociceptive activity of diverse analgesics with their binding affinity to "opiate" receptors and their lipophilicity. BIBLIOGRAPHIC REFERENCES: May, E.L. and Jacobson, A.E.: The chemistry and pharmacology of homologs of 6-acetyl and 3,6-diacetylmorphine. J. Pharm. Sci. 66: 285-286, 1977. Rice, K.C., Klee, W.E., Aceto, M.D., Swain, H.H. and Jacobson, A.E.: Potential long acting opiate antagonists: the preparation, pharmacological activity and opiate-recepter binding of N-substituted 2'-hydroxy-5-methyl-9 alpha-propyl-6, 7-benzomorphans. J. Pharm. Sci. 66: 193-197, 1977.